Single Phase to Three Phase Converter DIY

Written by wesley tucker | 13/05/2017
Single Phase to Three Phase Converter DIY
Three-phase power is needed to run large production machinery. (electricity image by Greg Pickens from

Three phase power is a 220-volt electrical installation. Heavy machinery and some large heating and air conditioning units need three phase power to operate. Although some machines will turn on with single phase power, the necessary "horsepower" to do work is lacking. If a building or other location does not have three-phase power available, a three-phase converter can be installed to supply the necessary electricity.

220 Volt Access

The location for the machinery must have 220-volt power supply with the recommended amperage (usually 30 to 50 amps) before the converter can be installed. If there is no 220-volt power outlet, start by installing the 220-volt line to the location needed. Find an open circuit in the circuit breaker box, install the 220 breaker (usually requiring two single phase lines from the main breaker), and attach the 22-volt wire. Run this cable either through electrical conduit (pipe) or an overhead space to the proper location.

Install a 220-volt two-phase junction box to connect the power line to the converter. The box should be wall mounted and close enough to the converter to avoid long power lines needing to be either run through walls or conduit.

Three-phase Converter

The converter is a machine about the size of a 10-gallon water cooler. All power to and from the converter is hard wired (meaning no electrical sockets.) The three-phase converter will come with a wiring schematic for properly connecting the black, red, blue and neutral white lines to the junction box. Again, hard wire all connections according to local building and electrical codes.

Connecting Machinery

If the machine has an electrical plug, remove it and access the wires inside the power cable. There is a junction box on the converter for connecting the machine. Access the junction, and again, use the schematic diagram to connect the machine. There is a chance the power wires are different colours if the machine being powered is imported from Europe or Asia. European standards for three-phase power are brown, black, grey and neutral blue. Asia uses yellow, green, red and neutral light blue.

It's important to wire the machine correctly to the converter because mixing a wire can have a very obvious effect: the machine will run backwards. Although this might not be a problem with some machines, having a compressor or stamping press go the wrong way could lead to serious damage to the machine. Connect the wires in the proper sequence, and power up the converter at the circuit breaker. The converter only runs when the attached machine operates, so there is no need to cut power at the breaker box every time the converter is not operating.

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